I'm seeing a rather odd hang with ksh 2014-06-06 on OS X 10.7.5 when using
the builtin cut and grep in a pipeline:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ type cut
cut is a shell builtin version of /usr/bin/cut
$ type grep
grep is a shell builtin version of /usr/bin/grep
$ cat pattern_file
x11 x12
$ cat file
x11
x21
$ cut -f 1 -d ' ' pattern_file | grep -Ff /dev/stdin file
...hang...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Using dtrace to get a stack trace of the ksh process during the hang reveals
the following:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ sudo dtruss -sp 7646
Password:
SYSCALL(args) = return
mmap(0x1E0962C49000, 0x700800000, 0x3, 0x1002, 0xFFFFFFFF, 0x6)
= 0x62C49000 0
libsystem_kernel.dylib`__mmap+0xa
ksh`_vmsegalloc+0x5b4
ksh`bestpackextend+0x1fb
ksh`bestpackalloc+0x379
ksh`bestalloc+0x245
ksh`bestresize+0x7d2
ksh`_ast_realloc+0x117
ksh`_sfexcept+0x3ff
ksh`sfwr+0x75a
ksh`_sfflsbuf+0x1b5
ksh`sfputr+0x1f8
ksh`addre+0x301
ksh`compile+0x2fe
ksh`grep+0xb0f
ksh`b_grep+0x1d2
ksh`sh_exec+0x2286
ksh`sh_exec+0x467a
ksh`sh_exec+0x53e8
ksh`exfile+0xe5b
ksh`sh_main+0x126a
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
Nathan Weeks
IT Specialist
USDA-ARS Corn Insects and Crop Genetics Research Unit
Crop Genome Informatics Laboratory
Iowa State University
http://weeks.public.iastate.edu/
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